Recently, a mom brought her 14-year-old daughter into my (Freda) Ob/Gyn clinic after just finding out that the girl was sexually active. In taking her sexual history I learned that the young lady had actually started having sex when she was 12 and in the two years since had 14 different partners. When I questioned her about the number of partners, her response was “Well, I only have sex with my boyfriend.”

Our popular culture had led her to believe that it was okay to have sex at 12 or 14 as long as you have a relationship with the person, and for her, it was okay because each guy she had sex with was, at the time, her “boyfriend.”

Now you can play it forward, as I did, and do the math and see how many partners she would have by 18 because obviously these relationships were not long term. So, it was instructive for me to talk to her and her mother about what this would mean to her body physically, psychologically and emotionally. And I had the scientific information to back it up.

One of the important things I had to help the mother understand was that studies have shown that parents are the most influential voice in the decisions of their children. I told the mother that she was actually abdicating her responsibility by bringing her daughter in, asking me to “help her to do what she is doing safely.” Instead, I asked the mother to think about “What is it that you desire for your daughter? What is it that you want to see her do?” Then I asked her to have that conversation with her daughter.

Unknown risks

Parents always find it hard to talk to children about sex. If they have a past of multiple sexual partners, it makes it doubly hard for them to talk to them, especially to give them good guidance—the kind of guidance that will lead them away from being involved sexually until they get married. But that past can also be their credibility. They don’t want their children to make the mistakes they have made.

For a young woman or young man with that kind of a history, the risk of sexually transmitted diseases is obviously very high. But there are also other emotional or physical risks that parents and children both need to be aware of that come with being sexually active outside of marriage as a teenager.

For example, when we do anything exciting, a hormone called dopamine is released in our brain that makes us feel like the world is good, that we have been a success. This hormone makes us want to repeat that activity.

Dopamine is necessary for us because it is what gives kids this excitement about leaving home and taking the huge risk of going out and being independent adults, which is a necessary part of growing up. But that hormone also can be negative because if a kid, for example, enjoys speeding at 100 miles an hour down a twisted road, he gets a dopamine kick for that, too. And the dopamine makes him want to repeat it.

When any of us have sexual intercourse, we have a huge outpouring of dopamine into our brains. It is released when a married couple has sex, which makes them want to repeat the sexual act which then allows them to get pregnant and have babies. But for the unmarried kid it makes him want to repeat that sexual act again and again. It is the same hormone that is secreted with addiction to drugs and nicotine.

Emotionally attached

Another thing teens may not understand is that even with one act of intercourse they will be emotionally attached to the person they are having intercourse with, and that these attachments can last a lifetime. During sexual intercourse, in the female brain there are more receptors for oxytocin, and in the male brain there are more receptors for vasopressin. Both hormones cause the person to feel emotionally attached to the other, even with just one act of intercourse.

So those in a relationship not only have the dopamine that rewards them for the repeating of the act, but also the oxytocin and the vasopressin that makes them feel attached. Thus, we have the name of our book Hooked. You become attached, addicted, bonded to each other.

In marriage, that is a good thing because you will stay attached to each other. Children are reproduced and you bond to those children, care for them, and help them grow up and our human race survives. But if you are 14 years old and have had 14 partners, and are still attached in some way to all 14 of them, you create problems.

All of this results in actual physical changes in the brain. When these hormones flow and send their impulses, they dramatically affect connections or synapses between the neurons in the brain. Those synapses actually are strengthened when we repeat a behavior or they are weakened when we stop. So, when you repeatedly attach and unattach with multiple sexual partners you actually weaken the ability to stay connected. Studies have shown that when people have had multiple sexual partners before marriage they are more likely to divorce because they actually weaken the pathways that are necessary to attach at the deep and necessary emotional level important for marriage.

The immature brain

One of the reasons parents are so important during their children’s adolescent years is because the Prefrontal Cortex – the part of the brain where we make rational decisions and where dopamine has its greatest influence – is not fully mature until the mid-twenties. Teenagers are not brain damaged. It’s just that they are not mature, and any parent of a teenager knows exactly what we are talking about. The growth of these synapses is increased before birth and again when they are in pre-puberty. Then, between puberty and the mid-twenties, the hardwiring is molded and “set” in its mature condition.

So, these adolescents need the judgment of parents to help them through those years with decisions about the future and to consider the consequences that they cannot fully see for themselves. Otherwise these mechanisms we have described as so important for marriage become a trap—an ambush of brain molding and a habit of behavior that can hurt them in ways they cannot imagine, not just for a few months but often for a lifetime.

We find that in every bit of this science we have looked at—the neuroscience, diseases, and so forth—that human beings are designed to be with one other person sexually and monogamously for life. The use of the term “design” calls to mind the intelligent design of God, but it is so amazing that even the secular reproductive anthropologists who would disagree with much of what we’ve said here use the word.

Based on the most modern neuroscience, sex is a whole body experience. The brain is the biggest and most important sex organ of the body. All these hormones in the brain and all these synapses that influence our habits and our patterns of living were designed by God so that we can be connected to one person for a lifetime in marriage.

As parents, that is our assignment: to guide our children so they can experience the very best thing that God has for them.

Adapted excerpt from Hooked by Dr. Freda Bush and Dr. Joe McIlhaney. Copyright © 2008 by Northfield Publishing; New Edition edition